Emissions from chimneys of a cement plant in Binzhou city, in eastern China's Shandong province. The UN says the world's climate change goal at now risk because emissions are surging, says the UN. Photo: AP

A global goal for limiting climate change is slipping out of reach and governments may have to find ways to artificially suck greenhouse gases from the air if they fail to make deep cuts in rising emissions by 2030, a draft UN report said.

A 25-page draft summary, by the UN panel of climate experts and due for publication next year, said emissions of heat-trapping gases rose to record levels in the decade to 2010, led by Asian industrial growth.

The surge is jeopardising a UN goal, set by almost 200 nations in 2010, to limit a rise in temperatures to below 2 degrees Celsius above levels before the Industrial Revolution, according to the text seen by Reuters on Friday.

The panel, made up hundreds of the world’s top climate scientists, is trying to condense all the peer reviewed findings since 2007 into a summary for policymakers.

Its draft said that if emissions were not checked by 2030, they would be so great that governments would have to take carbon dioxide out of the air to limit rising temperatures by the end of the century - not just cut emissions spewed from cars and factories - a sea change in the approach to climate change.

Governments must sign off on the document that emerges from the draft by Working Group Three of the Intergovernmental Panel on Climate Change and which will serve as the climate policy road map for the next six or seven years.

Delaying deep cuts until 2030 may make targets for limiting warming by 2100 “physically infeasible without substantial overshoot and negative global emissions ... in the second half of the century”, it said.

“Negative emissions” mean policies such as planting more forests that naturally absorb carbon dioxide from the air as they grow or burning biofuels, for instance wood or farm waste, and capturing and burying their greenhouse gas emissions.

Temperatures are already 0.8 C above pre-industrial levels and creeping higher despite a slowdown since around 2000, perhaps caused by more sun-dimming pollution from nations such as China and India that would reflect heat back into space or by more heat entering the oceans.

Most climate experts say the rising trend will pick up in coming years, though the reasons for the pause are unknown. Parts of Europe are having a late spring, for instance, while Australia suffered record summer heat.

Almost 200 nations have agreed to work out by 2015 a new deal to combat climate change that would enter into force from 2020. Negotiations are sluggish, partly because the slowdown in warming has made many governments sceptical.

The draft, dated Feb. 25, lays out options such as a shift to nuclear power from fossil fuels, more use of renewable energies, greater efficiency in building insulation, biofuels or a shift to vegetarianism to cut emissions by livestock.

It said it was hard to quantify the 2C target in practical terms, but said it was 60 per cent likely to be met if concentrations of greenhouse gases were kept below the carbon dioxide equivalent of 450 parts per million (ppm) of the atmosphere.

If concentrations rose to 550 ppm, the probability of staying below 2C would be only 40 to 50 per cent. Carbon dioxide levels, driven up by fossil fuels burnt in factories, cars and power plants, are now almost 400 ppm and steadily rising.

Scenarios showed that cuts of between 15 and more than 50 per cent below 2010 levels by 2030, along with shifts to renewable energies, would be needed to limit concentrations to 450 ppm by 2100, it said.

A previous report by the panel in 2007 said tough action to rein in climate change would cost less than 3 per cent of global gross domestic product by 2030, slowing growth by less than 0.12 per cent a year.

The new report does not give a direct comparison, but says a 450 ppm goal could be reached at a cost of less than 4 per cent of GDP.

Another section of the draft, which is still subject to changes and revisions, was leaked in December by climate change sceptics.

It said it was “extremely likely” that human activities had caused more than half of the observed increase in global average surface temperatures since the 1950s.

The Intergovernmental Panel on Climate Change and several climate scientists declined comment on the draft, saying they would wait until final publication.